tests: avoid spurious failure in 'parallel-tests3.test' This fixes automake bug#8788. * tests/parallel-tests3.test: To ensure that the serial run of the dummy testsuite is still ongoing when the parallel run has terminated, use `kill -0', not a bare `kill'. This will prevent a testsuite crash on NetBSD 5.1, and a testsuite hang on FreeBSD 8.2. Also, since we are at it, try harder to avoid possible hangs of the script in other unusual situations.